On February 19, 2009 18:20:33 Krasimir Angelov wrote:
Oh. I looked at the primops.txt.pp for something suspicious but I didn't checked the actual implementation of quot. I thought that quot calls quotInt# directly. When I use quotInt in the code I can get the real idiv assembly instruction. Still the code generated by GHC is strange it doesn't throw any exception actually. It just evaluates the same expression but with the constant maxBound.
On Thu, Feb 19, 2009 at 11:19 PM, Max Bolingbroke
a `quot` b
| b == 0 = divZeroError | a == minBound && b == (-1) = overflowError | otherwise = a `quotInt` b
I checked the quot one like you said. Kind of strange all right. It looks like it is performing the a == minBound check (where a = maxBound-x) despite the b == (-1) check (where b = 10) being optimized away. Cheers! -Tyson